At the cellular level, multiple gene expression changes have been linked to early onset of the disease: (a) the amyloid precursor protein (APP), a gene encoding a transmembrane protein that gets cleaved forming amyloid-beta (Aβ) which then accumulates and forms extracellular plaques; (b) Presenilin1 (PSEN1), subunits of the γ-secretase enzyme responsible for the cleavage of APP; (c) The microtubule-associated protein tau (MAPT), a gene encoding for the scaffold protein tau which tends to get hyperphosphorylated in AD and form neurofibrillary tangles [3]. The gene discussed is APP; the disease is Alzheimer disease.